AVS 50th International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI-ThM

Paper BI-ThM4
Simultaneous Atomic Force Microscopy and Fluorescence Imaging of Supported Biomembranes

Thursday, November 6, 2003, 9:20 am, Room 318/319

Session: Biosensors
Presenter: A.R. Burns, Sandia National Laboratories
Authors: A.R. Burns, Sandia National Laboratories
J.M. Gaudioso, Sandia National Laboratories
Correspondent: Click to Email
Lateral organization of lipids and proteins in membranes is critical to cellular signaling processes. Separately, fluorescence imaging and atomic force microscopy (AFM) are both effective ways to map structures in supported membranes. However, the ability to correlate information gathered from fluorescence imaging of labeled biomolecules and lipids with detailed lateral structures mapped out with AFM is highly advantageous. We discuss simultaneous AFM and submicron confocal fluorescence imaging of domain structures in model lipid bilayers. Lipids labeled by fluorescent probes either at the headgroups or tailgroups enable domain contrast in fluorescence imaging on the basis of partitioning between gel and disordered liquid phases. However, correlation with AFM topographic information reveals that they do not always faithfully report exact gel domain size or shape. Furthermore, we find that the fluorescence contrast decreases significantly with domain size, such that small domains observed with AFM are not observed in fluorescence images despite adequate optical resolution. Imaging of labeled proteins bound to membrane receptors is also discussed. In all cases, the complete correlation of topographic and fluorescence images provides evidence that gel-phase domains occur across both leaflets of the bilayer. This research was supported in part by the Division of Materials Science and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract DE-AC04-94AL85000.